Thank you very much for your feedback!
I tried to replicate the bug you mentioned and failed to crash the game (I'm terrible at playtesting). But I think I understand what might have happened: I didn't disable the coal collision while the goblin is holding it. This must be generating several collision calls, and as you reported that the coal kept spinning, this only reinforces the problem. Thanks for the report!
Regarding the audio: I liked your suggestions, I'll test and adjust the sound level. If not, I'll try to compose something new.
I really appreciate your comments!